Traditionally arterial punctures have been managed by the application of manual pressure at the puncture site, immediately after withdrawal of the intra-arterial catheter. By applying such manual pressure a seal is formed, made up principally of blood elements, thereby preventing the undesired escape of blood from the artery.
Although the application of manual pressure to the area of an arterial puncture has proven satisfactory in many applications, such a procedure does have a number of drawbacks. First, the person apply such pressure often experiences undue hand and arm muscle fatigue. Second, since the pressure is applied manually it is difficult to maintain a constant and controlled pressure at the puncture site. This can result in the application of a pressure which is too high, thereby cutting off desired blood flow through the artery. Third, the use of skilled personnel to apply pressure is an undesirable cost factor.
To overcome the above deficiencies it has been suggested in the prior art to provide mechanical devices for applying pressure at the site of an arterial puncture. Exemplary prior art devices are disclosed in the U.S. Pat. Nos. 3,625,219, (Abrams); Semler, 3,779,249; McRae et al., 4,233,980; Sahota, 4,509,528 and Royse, 4,572,182. These prior art devices include pressure applying members which either are in the form of rigid, substantially planar disks or are in the form of inflatable pads. The use of rigid disks, which do not include any fluid in them, may not result in symmetrical pressure application, due to the rigidity of the pad and the normal inconsistency of the body tissue. Moreover, applying compression with a hard, non-yielding member may cause undue discomfort to a patient.
A disadvantage of the prior art devices employing inflatable pads is that the overall structure is generally complicated by the fact that an inflating system needs to be included as part of such devices. Moreover, inflatable pads may be subject to undesirable leakage, with possible complications.
When a clamp or other device is employed at the site of an arterial puncture it is highly desirable to monitor the rate of blood flow through the artery being compressed, as well as the magnitude of the applied pressure. In this manner an operator can determine the desired pressure for preventing an undesired decrease in the rate of blood flow through the artery.
The earlier-identified patent to Sahota, U.S. Pat. No. 4,509,528, discloses a hemostat which includes a blood flow sensor employing the Doppler effect fastened at an angle within a small recess in the bottom pressure-applying wall of the rigid pressure disk. In addition to the disadvantage of employing a rigid disk, as discussed above, the inclusion of an angled sensor in the bottom surface of the pad also is considered by applicant to be an undesirable arrangement. First, due to the location of the sensor on the bottom wall of the pad it may share in the bearing of the pressure exerted against the patient. This could possibly result in damage to the sensor. Second, due to the angular position of the sensor relative to the pressure-applying surface of the disk, it may be difficult to exactly locate the proper region for applying the pressure, particularly in overweight people wherein the distance between the pressure applying surface of the pad and the artery to be compressed is increased. Third, it may be cumbersome to clean and sterilize the pressure disk and Doppler center. Fourth, repeated use of objects that come into contact with human blood, such as the pressure disk in Doppler center disclosed in the Sahota '528 patent, is inadvisable, and use of disposable disks with a Doppler center may be excessively expensive.
It also is known to employ the Doppler effect to detect the pulse of a patient as part of a diagnostic system, as is exemplified by the system disclosed in the patent to Russell, U.S. Pat. No. 4,154,231. In this latter device a water-filled glass tube includes a rubber membrane at one end thereof for the purpose of detecting a pulse. This device has absolutely no therapeutic use, and is neither designed nor capable of exerting the high compression forces required to be employed in a manometric dressing of the type forming the subject matter of the present invention.
In Chen et al., U.S. Pat. No. 4,579,123 there is disclosed a device which is a stand-off unit for a transducer employed to image internal body parts. Chen et al. states that an important feature of this type of system is to avoid the need to apply a firm pressure to the device, since applying such a firm pressure would disturb the relative locations of structures in the body. Chen et al. also states that it is important that the liquid 23 not completely fill the cups 2 and 22.
Kawabuchi, U.S. Pat. No. 4,677,853 discloses an ultrasonic probe for use in an ultrasonic diagnosis device. This probe is capable of operating in a pulse-doppler mode or a continuous-doppler mode. The ultrasonic probe disclosed in the Kawabuchi '853 patent lacks the arrangement of elements forming the subject matter of the present invention.